1. Field of the Invention
The invention pertains to the art of drive and safety release arrangements for tow carts.
2. Description of the Prior Art
As is well known in this art, an in-floor, tow-line cart system includes a number of tow trucks or carts which are driven by a below floor conveyor system which engages the bottom end portion of a tow pin or drive pin which extends down from the cart through a slot in the floor. These systems include main lines and spur lines to which the carts may be switched. It is common in such systems to provide bumper arrangements and cooperating mechanism which permit a number of successive carts to be accumulated and stop if the first cart has encountered an obstacle. Such arrangements typically provide for lifting the tow or drive pin out of engagement with the conveyor, but not out of the slot in the floor. Some arrangements also include a means for braking the carts. Examples of U.S. patents disclosing such arrangements generally are: U.S. Pat. Nos. 3,659,530; 3,581,670, 3,547,043 and 3,467,023.
Most of the tow-line systems that we are aware of are used, to the best of our knowledge, in warehousing type of operations in which the storage and handling of material is the principal function of the operation. In other words, those people in the vicinity of the tow-line system are mainly concerned with the operation of the system itself to accomplish the handling of the material carried by the system. However, tow-line systems may also be used in manufacturing installations where the tow line brings material to a machine operator whose principal concern is with operating a machine, rather than the handling of the material being performed by the tow-line system. In other words, where a tow line is provided in a warehousing operation the personnel are watching the operation of the tow line, whereas in a manufacturing operation the personnel are not watching the operation of the tow line. Therefore the problems of personnel safety arising from the use of a tow-line system in a manufacturing operation, as contrasted to a warehousing operation, is significantly greater.
It is our view that the release mechanisms of the types illustrated in the noted patents, as well as others available in commercially available tow-line systems, may be adequate in a warehousing operation but are inadequate from the standpoint of personnel safety in a manufacturing operation. We believe this to be so because the degree of obstruction required with these prior art arrangements to effect the release of the drive pin from the conveyor means is sufficiently great that if the obstruction were a person the person could be severely injured before the release was effected.
Thus an aim of our invention is to provide a drive pin release arrangement capable of being actuated with a lesser degree of obstruction than those arrangements of which we are aware, to the end of reducing the chance and severity of personnel injury from the cart.